Infertility, a disorder of the reproductive system, is commonly linked to hormonal, pituitary, cervical, uterine, immunological or psychological factors. Besides these factors, it can also be idiopathic or unexplained. Hence, there is a need for more research to unravel the causes of the unexplained infertility. This work aimed at finding out whether there is any relationship between ABO blood group system and female infertility. The study design was cross-sectional. Three hundred women between 18 and 40 years attending fertility clinic at the University of Calabar Teaching Hospital, Calabar between 2011 and 2012 were recruited for this study. Serum progesterone, prolactin, follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol were determined using Enzyme linked immunosorbent assay (ELISA) while ABO blood grouping was determined using the tube method. Statistical analysis was done using SPSS version 18. The confidence level was set at 95% where p-value less than 0.05 was considered statistically significant. The mean age of the women was 30.65 ± 5.47 years and the percentage distributions of the blood groups among the women were as follows: 24% A, 12% B, 4% AB and 60% O. The mean FSH levels of blood groups A and O individuals were significantly higher (p<0.05) than that of groups B. However, there was no significant difference (p>0.05) in the mean levels of progesterone, prolactin, LH and estradiol in the respective groups. From this study, 38% of the population had increased levels of progesterone, 58% and 18.7% had elevated prolactin and FSH levels respectively while 11.33% and 43.3% had reduced levels of LH and estradiol levels respectively. Though, there was high prevalence of hyperprolactinemia observed in this study, there was no strong association between ABO blood group and female infertility but, the increased FSH levels observed in blood groups A and O may be a potential link between blood group and infertility and therefore may be beneficial for further study.